The natural velocity profile of exhaust gas in a muffler flowing towards the inlet of an exhaust aftertreatment device (e.g., a catalytic converter or diesel particulate filter) resembles a parabolic curve with the velocity maximum at the center of the flow distribution and decreasing significantly outwardly towards the periphery of the flow distribution. This non-uniform velocity flow distribution shortens the useful lives of the aftertreatment devices, and reduces their operational efficiency.
Various flow distribution devices have been used to create a more uniform velocity flow profile. U.S. Pat. Nos. 5,355,973; 5,732,555; 5,185,998; and 4,797,263 disclose exemplary flow distribution devices that can be used to prolong the useful life and efficiency of exhaust aftertreatment devices. However, these flow distribution devices typically either impede fluid flow causing an undesirable increase in backpressure or do not adequately distribute flow across the face of their corresponding exhaust aftertreatment device. Consequently, there is a need for improved flow distribution devices that provide an effective flow distribution while at the same time generating reduced backpressure.